Author: Carla Sofia
A LCD liquid crystal display crystal is a fine panel, used to exhibit information for electronic road, as text, images and videos. His/her use includes monitors for computers, televisions, panels of instruments and other devices, that space from cockpit of aircrafts, displays in computers of board of automobiles, to devices of use daily rates, such as video readers, devices of games, clocks, calculating and telephones.
A LCD consists of a liquid polarizador of the light, electrically controlled, that he/she is compressed inside of cells among two sheets transparent polarizadoras. The axes polarizadores of the two sheets are aligned perpendicularmente amongst themselves. Each cell is provided of contacts eléctricos that allow an electric field to be applied to the liquid in the interior.
Among their main characteristics it is his/her levesa, his/her portability, and his/her capacity of being produced in much larger amounts than the tubes of rays catódicos (CRT). His/her low electric power consumption allows to be him/her used in portable equipments, fed by electronic battery. It is a modulated electronic-optical device, composed by a certain pixels number, filled out with liquid and willing crystals in front of a light source to produce images in colors or black and white.
The oldest discovery than it took to the development of the technology LCD, it was the discovery of the liquid crystals, in 1888.
In 2008, the world sales of televisions with screens of LCD overcame the sale of units CRT.
A monitor of liquid crystal is a very light and fine monitor, without movable parts.
The technology LCD is already used there is some time. As example, we can mention portable consoles that began in Gameboy (Nintendo), clocks digital, calculating, mp4, mp3, portable DVDs, digital and cellular cameras.
Advantages
1. The monitors of the type LCD possess a screen that is really plane, eliminating the distortions of image of the monitors of the type tube of rays catódicos, or CRT (that you/they have their curved screens);
2. They tire less the view;
3. They consume less energy;
4. They emit little noxious (some models no longer they emit noxious radiation some) radiation;
5. Recent models have corrections of distortions, leaving the images in harmonic and more real state, even in movement.
Disadvantages
1. They have the limited angle to a perpendicular (90th) vision, suffering with the problem of the black light and white light, although that just happens in older models. Nowadays, most of the monitors of LCD arrives to 178th of vision.
2. The persistence of the logical state of the pixels LCD can take to effects of I “drag” in the exhibition of images with movement.
3. The resolution is not constant, with losses of 50% in images in movement (in older models).
4. He/she doesn’t have good definition with sources SDTV: Open TV and analogical cable, DVD, SKY SD (480i).
General vision
Each pixel of a LCD typically consists of a layer of aligned molecules between two transparent electrodes and two filters polarizadores. The transmission axes, are in most of the perpendicular cases each other.
The surface of the electrodes that you/they are in contact with the material of liquid crystal is treated from way to align the molecules of liquid crystal in a certain direction. This treatment consists typically of a fine layer of polymeric that unidirecionalmente is scrubbed. The direction of the alignment of the liquid crystal is defined then by the direction of the friction.
The electrodes are made of a called transparent driver Indium Tin Rusts (ITO). Before applying an electric field, the orientation of the molecules of liquid crystal it is certain for the alignment with the surfaces of the electrodes.
In a device “twisted nematic”, (device more common of liquid crystal) the alignment directions in the surface of the two electrodes are perpendicular each other, and like this the molecules are organized in a helical structure.
This reduces the rotation of the polarization of the incident light, and the device appears ash. If the applied tension to the surface is big, the molecules of liquid crystal in the center of the layer assume helical form almost completely, and the polarization of the incident light doesn’t turn as it passes through the layer of liquid crystal, this light will be, then, mainly polarized perpendicular to the second filter, and, therefore, he/she will appear the black pixel.
When controlling the applied tension in the whole layer of liquid crystal in each pixel, the light can be authorized to pass in varied amounts constituting different ash levels.
The optical effect of a device twisted nematic in the tension and in the state, it is much less dependent of the variations of the thickness of the device than of the tension in the turned off state.
Due to this, these devices are usually operated among crossed polarizadores in such a way that they appear diamonds without tension (the eye is much more sensitive to the variations of the dark state than to the brilliant state).
These devices can also be operated among parallel polarizadores, I marry in that the clear states and darkness are inverted. The tension of state turned off darkness in this configuration appears spotted, however, due to small variations of thickness in the whole device.
As much the material of liquid crystal as the material of alignment layer it contains composed ionic. If an electric field of a specific polarity is applied by a long period of time, this ionic material is attracted for the surface and it degrades the acting of the device.
That is avoided, through the application of an alternating current or inverting the polarity of the electric field, as the device is the addressee (the answer of the layer of liquid crystal is identical, independently of the polarity of the applied field).
Brief history
1888: Friedrich Reinitzer (1858 -1927) he/she discovers the nature of the extracted of carrot (in other words, two coalition points and of generation of colors) crystalline liquid of cholesterol and it published their discoveries in a meeting of the Chemical Society Vienna on May 3, 1888 (F. Reinitzer: Beiträge zur Kenntniss give Cholesterins, Monatshefte für Chemie (Wien) 9, 421-441 (1888)).
• 1904: Otto Lehmann publishes his/her work “Flüssige Kristalle (Liquid Crystals).”
• 1911: Charles Mauguin accomplishes first experiments of liquid crystals confined among the plates of fine layers.
• 1922: Georges Friedel described the structure and the properties of the liquid crystals and it classified them in 3 types (nemáticos, smectics and cholesterics).
• 1936: Marconi Wireless Telegraph patented the first practical application of the technology, “The Liquid Crystal Light Valve.”
• 1962: The first publication in important English language on the theme Molecular “Structure and Properties of Liquid Crystals”, for the Dr. George W. Gray.
• 1962: Richard Williams, of RCA discovered that the liquid crystals had some characteristics interesting optical electro, generating stripe-patterns in a fine layer of material of liquid crystal through the application of a voltage. This effect is based now on hydrodynamic eletro-instability forming what is called inside of “domains Williams” of the liquid crystal.
• 1964: George H. Heilmeier, working at the laboratories of RCA on the discovery of Williams got the change of colors for the field, induced the realinhamento of coloring dicróicos in a crystal liquid guided homeotropically, what generated the accomplishment of the first display of operational liquid crystal based on which he called dynamic way of dispersion (DSM).
Application of a tension to a display DSM changes the initially egg white layer of transparent liquid crystal in a state of turbidity leitosa. He/she exhibits that DSM could be explored of way transmissivo and reflexive, but they demanded a considerable current of flow for his/her operation. George H. Heilmeier was included in National Inventors Hall of Fame and credited with the invention of LCD.
• 1960: I work pioneering on the liquid crystals was accomplished in the end of the years 1960 by the Constitution of Reino Radar Royal in Malvern, in England. The team of RRE supporting the work in course of George Gray and his/her team of the University of Hull, that finally discovered CYANOBIPHENYL liquid (that he/she had stability and properties of correct temperature for application in LCDs) crystals.
• 1970: On December 4, 1970, the effect of field twisted nematic in liquid crystals was patented by Hoffmann-La Roche, in Switzerland, (Swiss patent n º 532 261), with Wolfgang Helfrich and Schadt Martin listed as inventors [9]. Hoffmann-La Roche, soon afterwards, licensed the invention to the Swiss manufacturer Brown Boveri & Cie, that produced display for watches during the decade of 1970. The industry of electronic Japanese soon it produced the first clocks of digital quartz of pulse with TN-LCDs and many other products. James FERGASON while he/she worked with Sardari Arora and Alfred Saupe in Kent State University Liquid Crystal Institute presented an identical patent in E.U.A. on April 22 of 1971. [13] in 1971, FERGASON ILIXCO’S (now LXD Incorporated) company produced the first base LCDs on the TN-effect, that soon substituted the types of DSM, due to improvements of tensions, of operation and smaller consumption of energy.
• 1972: The first panel of the assets-main viewfinder of liquid crystal was produced in the United States by T. Peter Brody.
• 2007: In 4 º quarter of 2007, for the first time the sale of televisions LCD overcame her/it of CRT at world level.
• 2008: TVs LCD became most with a share of market of 50% of the 200 million TVs.
Article Source: http://www.articlesbase.com/technology-articles/lcd-liquid-crystal-display-1576355.html
About the Author:
Carla Sofia adores technology especially the technology LCD.Televisores LCD and see the Televisor Samsung LCD TV de 32 polegadas
